Shelves can be used to store and display various types of items. For example, shelves in an automotive mechanic's garage can be used to store and display tools and automotive parts. In a warehouse, shelves can be used to store items that can be later retrieved and shipped to other locations. As another example, shelves in a residence can be used to store items such as food and cleaning products.
Shelves can be mounted on a support structure that positions at least some of the shelves, and items stored thereon, above the ground surface. If a shelf is high enough above the ground surface, it may be difficult for a person or machinery to access and retrieve items that are stored on the shelf.